A U.S. congressional committee has demanded that former drug executive Martin Shkreli appear at a hearing on drug prices to testify about his former company's decision to raise the price of a lifesaving drug by more than 5,000 percent, congressional aides said on Wednesday.

Shkreli, who is separately facing federal criminal charges that he defrauded investors, has been served with a subpoena to appear on Jan. 26 before the U.S. House of Representatives' Committee on Oversight and Government Reform, the aides said.

Shkreli, 32, fired back at lawmakers on Twitter, writing on Wednesday that the House was "busy whining to healthcare reporters about me appearing for their chit chat next week. Haven't decided yet. Should I?"

The outspoken entrepreneur sparked a firestorm last year after he raised the price of Daraprim, a decades-old treatment for a dangerous parasitic infection, to $750 a pill from $13.50 after acquiring it. The medicine once sold for $1 a pill.

Shkreli pleaded not guilty last month to criminal charges that he ran his companies like a Ponzi scheme, using each subsequent company to pay off defrauded investors from a prior company.

After his arrest, he stepped down as chief executive of Turing Pharmaceuticals and was fired as chief executive of KaloBios Pharmaceuticals Inc. KaloBios also filed for Chapter 11 bankruptcy.

Shkreli's past companies also include Retrophin Inc., which sued him for alleged mismanagement.